1. Field of the Invention
This invention relates to a method of burnishing brake pads, and more particularly, to a method of burnishing brake pads using a high intensity heat source. The invention also relates to a pre-burnished brake pad.
2. Description of Related Art
New brake pads have a low coefficient of friction, typically less than 75% of a burnished pad. To increase the coefficient of friction, the new brake pads require a break-in treatment, otherwise known as a burnish, which consists of several hard stops before the coefficient of friction increases to a stable level, otherwise known as the steady state.
The ability of vehicle drivers to carry out a successful break-in varies widely. Therefore, automobile manufacturers prefer that the brake pads be pre-burnished to increase the coefficient of friction before they are mounted on the vehicles.
Conventional methods of pre-burnishing include burnishing the brake pads on a brake dynamometer by engaging the brake pads onto a rotor therebetween, flame scorching, and searing on a hot plate. These types of pre-burnishing treatments are not precise and are very inefficient and costly.
The article entitled "SAP Technical Paper Series" by David T. Patten in the SAP The Engineering Resource For Advancing Mobility, Feb. 24-28, 1986 discloses that lasers with a power source up to 100 Mw/m.sup.2 have been used unsuccessfully to pre-burnish brake pads. The increase in friction provided by applying a laser having less than 100 Mw/m.sup.2 only provides an increase in the coefficient of friction of 20%. This article further teaches that a medium power laser (less than 100 Mw/m.sup.2) is preferred because it provides a 20% increase over a high power laser (less than 100 Mw/m.sup.2 but greater than the medium power laser) which only provides a 17% increase in the coefficient of friction.
There is a great need for a simple and fast method of pre-burnishing brake pads which increases the coefficient of friction by at least 25% over the initial coefficient of friction, or which increases the coefficient of friction to an adjustable level of desired initial friction to within about 15% of the long-term steady-state coefficient of friction.